Generally, a flat panel display (FPD) refers to an image display that is thinner and lighter than a television or monitor using a cathode-ray tube. Such a FPD includes a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED) and an organic light emitting diode (OLED).
Among them, the LCD is an image display device capable of displaying a desired image by controlling light transmissivity based on data signals according to image information provided to liquid crystal cells aligned as a matrix-type. The LCDs have been used broadly because they are thin and light with low power consumption and low operation voltage consumption.
A method for manufacturing a conventional liquid crystal panel typically used in such the LCD will be described as follows. First of all, color filters and common electrodes are formed on a top glass substrate according to a preset pattern. Hence, thin film transistors (TFT) and pixel electrodes are formed on a bottom glass substrate facing the top glass substrate according to a preset pattern. After that, an alignment layer is coated on each of the substrates and the alignment layer is rubbed to prove a pretilt angle and an alignment direction to liquid crystal particles of a liquid crystal layer formed between the substrates.
Sealant paste is coated on either of the substrates according to a preset pattern by a dispenser, to maintain cell gaps and prevent the liquid crystal from leaking outside and to keep sealing between the substrates airtight. In this instance, a process of dotting conductive paste is further performed to connect the common electrodes with the pixel electrodes formed on the substrates, respectively.
Hence, the liquid crystal layer is formed between the substrates and a liquid crystal panel is manufactured. In this instance, liquid crystal injecting and liquid crystal dispensing are used for forming the liquid crystal layer.
In this instance, in the liquid crystal injecting, the substrates are adhered to each other and liquid crystal is injected between the adhered substrates via an injecting hole formed in the substrates and the liquid crystal layer is formed after the injecting holes are sealed airtight. In the liquid crystal dispensing, liquid crystal is dispensed to a preset space defined by sealant of the substrate by using an apparatus of dispensing crystal dispensing. After that, the substrates are adhered to each other and the sealant is hardened to bond them.
Meanwhile, as the liquid crystal display panel has been getting enlarged and mass-productive, there may be a method for dispensing liquid crystal on the substrate to fill the liquid crystal. In this method, a sealing material is formed on an edge region of a thin film transistor substrate or a color filter substrate and the liquid crystal is dispensed. After that, the two substrates are adhered to each other in opposite and the liquid crystal is disposed between the two substrates.
In the process of manufacturing the liquid crystal panel, the liquid crystal dispensing device is used to dispense the liquid crystal and the apparatus of dispensing crystal dispensing includes a nozzle that exhausts the liquid crystal transported from a syringe storing the liquid crystal on a substrate, while relative-moving with respect to the substrate.
In the apparatus of dispensing crystal dispensing, the amount of the liquid crystal fully stored in the syringe is gradually reduced as the liquid crystal is exhausted from the nozzle. Accordingly, the pressure in the syringe is changed and it is impossible to exhaust a preset amount of liquid crystal via the nozzle.
This might deteriorate the quality of the liquid crystal panel. Accordingly, it is necessary to maintain the pressure in the syringe uniformly while the liquid crystal is exhausted via the nozzle. Especially, as the desired amount of the liquid crystal exhausted via the nozzle is getting smaller, such a disadvantageous phenomenon might be getting worse even in a minute pressure change in the syringe. It can be said that such the necessity is quite important.
As mentioned above, the liquid crystal is dispensed one by one lump anisotropically in the apparatus of dispensing crystal dispensing adapting the liquid crystal dispensing method. However, the liquid crystal contained in one lump might be distributed unevenly. As the liquid crystal is spreading, the density of the liquid crystal might be different for each of points.
As a result, a physical property of the liquid crystal such as viscosity might be changed and the physical property of the liquid crystal might be varied with respect to an entire liquid crystal panel. Accordingly, dispensing spots that makes a clean image quality difficult to gain might be generated.
Meanwhile, in reference to FIGS. 1 and 3, a process of dispensing the liquid crystal on the substrate by using the conventional apparatus of dispensing crystal dispensing will be described as follows.
As shown in FIG. 1, the apparatus of dispensing crystal dispensing 10 is arranged beyond a substrate (S). Although not shown in the drawings, liquid crystal (L) is filled in the apparatus of dispensing crystal dispensing 10 to dispense a preset amount of the liquid crystal on the substrate (S).
Typically, the liquid crystal (L) is dispensed on the substrate (S) in a droplet shape. The substrate (S) is conveyed according to a speed preset along x and y directions of orthogonal coordinates and the apparatus of dispensing crystal dispensing 10 exhausts the liquid crystal (L) at preset regular time intervals. Accordingly, the liquid crystal (L) dispensed on the substrate (S) is arranged at preset intervals along x and y directions.
In this instance, the substrate (S) is fixed while the liquid (L) is dispensed. The liquid crystal (L) may be dispensed at preset intervals while the apparatus of dispensing crystal dispensing 10 is conveyed along x and y directions.
The liquid crystal (L) is dispensed on the substrate (S) by the apparatus of dispensing crystal dispensing 10 in a droplet shape. When the circular-shaped liquid crystal (L) is dispensed on the substrate (S) as shown in FIG. 2, a square in contact with the circular liquid crystal (L) may be assumed. In this instance, there might be a region where the liquid crystal (L) is not distributed and the region is as far as a distance (a) from the liquid crystal (L) to a corner of the square.
When the liquid crystal (L) is dispensed on the substrate (S), a plurality of liquid crystal droplets may be dispensed as shown in FIG. 3.
Accordingly, there might be on the substrate (S) the region where the liquid crystal (L) is not distributed. If the liquid crystal droplets are overlapped to prevent the region, there might be too much dispensed liquid crystal (L) disadvantageously.